SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c1de358d19ed22efd694396990faa54bb60e99f04bf0de1def23071931d3d4c9' 
  AND token = 'lmir+479A9w/X31yVOS/6jbTMJGEbSCotcCLxsFIwTo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}